You can use 2.6.19 later kernel and enable HT_IRQ in it. --- Eric worked it out, and I didn't have chance to test it.
Hey, 2.6.19.1 actually boots (better than 2.6.19)! 2.6.19.1 with HT_IRQ turned on yields:
sh-3.1# modprobe ib_ipath PCI: No IRQ known for interrupt pin C of device 0000:40:01.0. Probably buggy MP table. mtrr: type mismatch for fd500000,100000 old: write-back new: write-combining ib_ipath 0000:40:01.0: mtrr_add() WC for PIO bufs failed (-22) ib_ipath 0000:40:01.0: infinipath0: Write combining not enabled (err 22): performance may be poor
Note that HT_IRQ removes the complaint (formerly right before the mtrr complaints):
ipath_core 0000:40:01.0: infinipath0: irq is 0, BIOS error? Interrupts won't work
Further fun stuff to try? I am your board monkey.
-mcq